The brain stem central tegmental field (FTC) has the potential to influence upper arway patency and diaphragmatic efforts. Its overall effect is excitatory to inspiration. These results relate to the control of breathing during sleep and wakefulness since the FTC is the anatomical substrate of the reticular activating system which is essential for waking consciousness. We propose to determine the relationship of the FTC to other respiratory structures. Stimulation of the FTC can produce switching from one phase of breathing to the other. This phase-switching could be mediated by the pneumotaxic centers. Similarly, other midbrain efforts on respiration may be mediated by vagal or thoracic reflexes. To answer tese questions, the influence of FTC stimulation on breathing will be investigated in anesthetized animals with bilateral pneumotaxic center brains, transection of the spinal cord at C8 and bilateral interruption of vagal afference. We propose to study the relationship between the FTC and both vagal motoneurons and other respiratory neurons during sleep-wakefulness. We want to determine if those respiratory neurons which are decruited in sleep and recruited in wakefulness are closely and preferentially related to he FTC. If true, this would establish a link in the mechanism which produces the more vigorous breathing of wakefulness.